- Central cornea thickness (CCT) is regarded as an indispensable investigation in the workup of any glaucoma suspect patient.
- There are several biological factors and genetic components that may influence glaucoma progression, which have been associated with thinner CCT.
- The CCT itself can be affected by several factors including ethnicity, age, sex, glaucoma medications, genetics, and the subtype of glaucoma.
- There is also variability in the measurement of CCT between difference types of devices.
- These factors need to be considered in the evaluation of glaucoma patients' CCT and its effect on interpretation of intraocular pressure (IOP) levels and risk stratification.
- Thinner CCT is found more often in patients with normal tension glaucoma (NTG) and angle closure, African American and Japanese patients, those with more advanced glaucoma and is an independent risk factor in ocular hypertension (OHTN).
- Its predictive value in established glaucoma is not proven; however, it is important in interpreting IOP results and risk stratification.
- The association of CCT with biological factors and genetics in glaucoma will hopefully become clearer as the research expands in these areas.
- The use of devices that measure IOP independently of CCT would help to overcome its influence; however, they are still not widely incorporated into general clinical practice.
- Despite many proposed mathematical models, correcting Goldmann Applanation Tonometry (GAT) IOP does not provide any benefit in the assessment or management of glaucoma.
- Correcting methods introduce other errors into the interpretation of the IOP results. In addition, the adjusted IOP is unlikely to improve tonometry as a screening tool for open angle glaucoma (OAG) in at-risk populations and is not necessary in population-based assessment. Therefore, attempting to “correct” IOP based on CCT does not provide any benefit in the assessment or management in the glaucoma or glaucoma suspect patient.
REFERENCE:
Belovay GW, Goldberg I. The thick and thin of the central corneal thickness in glaucoma. Eye (Lond). 2018 May;32(5):915-923. doi: 10.1038/s41433-018-0033-3. Epub 2018 Feb 15. PMID: 29445115; PMCID: PMC5944650.
